TITLE:
Analysis of Non-Selective Catalyst Reduction Performance with Dedicated Exhaust Gas Recirculation
AUTHORS:
Chris A. Van Roekel, David T. Montgomery, Jaswinder Singh, Daniel B. Olsen
KEYWORDS:
Natural Gas Engine, Rich Burn, Dedicated Exhaust Gas Recirculation, Catalyst
JOURNAL NAME:
Advances in Chemical Engineering and Science,
Vol.12 No.2,
April
27,
2022
ABSTRACT: Rich burn industrial natural gas engines offer best
in class post catalyst emissions by using a non-selective catalyst reduction
aftertreatment technology. However, they operate with reduced power density
when compared to lean burn engines. Dedicated exhaust gas recirculation (EGR)
offers a possible pathway for rich burn engines to use non-selective catalyst
reduction aftertreatment technology without
sacrificing power density. In order to achieve best in class post
catalyst emissions, the precious metals and washcoat of a non-selective
catalyst must be designed according to the expected exhaust composition of an
engine. In this work, a rich burn industrial natural gas engine operating with
dedicated EGR was paired with a commercially available non-selective catalyst.
At rated brake mean effective pressure (BMEP) the air-fuel ratio was swept
between rich and lean conditions to compare the catalyst reduction efficiency
and post catalyst emissions of rich burn and dedicated EGR combustion. It was
found that due to low oxides of nitrogen (NOx) emissions across the
entire air-fuel ratio range, dedicated EGR offers a much larger range of
air-fuel ratios where low regulated emissions can be met. Low engine out NOx also points towards a possibility of using an oxidation catalyst rather than a
non-selective catalyst for dedicated EGR applications. The location of the NOx-CO
tradeoff was shifted to more rich conditions using dedicated EGR.